For most people, the world of grammar can be a mysterious place. There are hundreds, if not thousands, of rules you have to memorize that cover everything from verb conjugation to spelling changes to run-on sentences. It's not surprising, then, that there are also lots of misconceptions about grammar. Advice that's outdated or just plain incorrect gets picked up and passed along from student to student, and often even in the classroom. Below you'll find ten of these grammar myths along with advice on how to avoid making these common writing mistakes.

Myth #1. A sentence can't end with a preposition.

This is a big one. Most of us are taught in school that we shouldn't end sentences with prepositions, for example, instead of "What is that tool used for?" we would say "For what is that tool used?" (Remember, a preposition is a word that describes the temporal or spatial relationship between things, for example before, under, around, for, and at).

The myth of the sentence-ending preposition can be traced back to a 17th century poet and playwright named John Dryden who claimed that English sentences shouldn't end in prepositions because it violated Latin grammar rules. Over a hundred years later, the 18th century bishop Robert Lowth would popularize the rule by including it in his widely-read grammar book. The problem with this rule, however, is that English isn't derived from Latin. It's Germanic, the same language family as German, Dutch, and Afrikaans, and in these languages it's perfectly acceptable to end sentences with a preposition.

In fact, most style guides will allow for a preposition at the end of a sentence as long as it's necessary to keep the meaning of the sentence intact. For example, in the sentence "Where are you going to?" the preposition to isn't necessary; the sentence still makes sense if it reads "Where are you going?" Therefore, that preposition should be left out. On the other hand, in the example from above, "What is that tool used for?" the sentence wouldn't make sense without the preposition: "What is the tool used?" In this example, the preposition can stay.

Myth #2. None is always singular

Words that describe groups can be tricky to conjugate. For example, the collective noun class can be either singular or plural, depending on how it's used:

The class is going to be meeting 15 minutes late today.
(Singular, because the class is acting as a whole.)

The class got out their pencils and got ready for the test.
(Plural, because the members of the class are acting as individuals.)

This ambiguity can be especially troublesome with nouns like everyone, no one, and all when it's unclear who or how many things they refer to. None is a prime example of this problem. Most students are taught that the word none replaces the phrase not one, and should therefore be singular. For example, if you'd say "Not one cousin is coming to my wedding," then it would make sense to say "None of my cousins is coming to my wedding."

But the word none is actually derived from an old English phrase that means no people or not one of a group of things, which makes none plural. If we say "Not one of my cousins are coming to my wedding" or "no people are coming to my wedding," then it makes more sense to say "None of my cousins are coming to my wedding."

The only time none should be singular is when it refers to an uncountable noun (a noun that is measured as an amount instead of a number). For example, you would say "None of the milk has spilled" (singular has) instead of "None of the milk have spilled" (plural have).

Myth #3. You should never use passive voice.

Passive voice is frowned on in many types of academic writing because it can lead to wordy and vague sentences. When you say "Hamlet's mother is blamed for her husband's death," you've left out vital information: who is doing the blaming? It's much more clear to simply state "Hamlet blames his mother for his father's death."

However, there are some circumstances in which it's acceptable to use passive voice. The biggest exception to the "active voice only" rule is scientific writing. When writing about original investigative work, the use of the passive voice is often encouraged to create distance between the author and the results and to make the work seem impartial. So, in science writing you would write "The treatment was applied three times daily" instead of "We applied the treatment three times daily."

The passive voice can also be used if the person performing the action isn't known. For example, you might say "My car was hit in the parking lot last night," because you don't know who hit your car.

Myth #4. A sentence can't start with a conjunction.

This rule is another favorite of English teachers everywhere: never start a sentence with a conjunction. Conjunctions are the words and, but, or, nor, yet, and so that are usually used to join independent clauses (clauses that can stand alone as sentences). For example, "My parents are going to see a play, but my sister and I plan to stay home" or "The fire was out, so we went to get more wood."

Your English teacher probably told you that that's all conjunctions are good for, but in fact there's nothing technically wrong with starting a sentence with a conjunction. You can write "My sister doesn't plan on going to the dance with anyone, but I think we can change her mind" or "My sister doesn't plan on going to the dance with anyone. But I think we can change her mind." Both sentences are correct.

Whether or not to use conjunctions at the start of a sentence is more of style choice than an issue of grammatical accuracy. Starting a sentence with and or but can add emphasis to a sentence, but it will also make your work seem more informal. Therefore, in academic writing it's generally better not to start sentences with a conjunction even though it's technically correct.

Myth #5. Infinitives can't be split.

As with the sentence-ending preposition rule, the ban on split infinitives comes from an incorrect reliance on the grammatical rules of Latin. In Latin, the unconjugated form of a verb (the infinitive) is one word, so obviously it can't be split. In English, however, the infinitive is formed using the form to + verb, making it possible to add modifiers between the two words. For example to quickly drive and to carefully describe are both split infinitives

In the 19th century, Henry Alford, a Latin scholar, wrote a popular grammar book that included a ban on split infinitives. The rule became popular in classrooms, but most grammarians and linguists say there's no basis for it, and most style guides will allow it. In fact, it often sounds better when the infinitive is split: "He wanted to quietly tell his sister that he needed her advice" is easier to read than "He wanted to tell his sister quietly that he needed her advice."

Myth #6. Whose can only refer to people.

We all know that whose is the possessive form of who. That's why we say things like "Whose shirt is that?" and "The girl, whose car had broken down, had to walk." But did you know that whose has historically also been the possessive form of what? For example, it's correct to say "The house, whose front door was wide open, had been abandoned." Often students are told that instead they need to say "The house, the front door of which was wide open, had been abandoned" even though it's clumsy and hard to read. So, while both are technically correct, using whose as the possessive of what will keep your writing clear and concise.

Myth #7. They can never be used as a single person, gender neutral pronoun.

This last one is tricky, because even professional linguists and grammarians can't agree on what to do about gender neutral pronouns. It's simple enough when you have a singular subject with a known gender because you can use either he or she, for example "If my sister doesn't hurry up, she'll be late for the concert" or "When my brother wants a new couch, he can buy mine."

Problems arise, though, if the gender of the subject is unknown because English has no gender-neutral pronoun. This ambiguity leaves you with two choices: the clumsy phrase he or she or the plural pronoun they: "If the student doesn't hurry up, he or she will be late for the concert." or "If the student doesn't hurry up, they will be late for the concert." English teachers will tell you that the first is correct, even if it sounds awkward, but that convention is slowly changing. Most style guides will now give you leeway to choose, and the use of the word they is already accepted in conversation and informal writing. English is an every-changing language, and this is one of those rules that's on its way out.